Patent US4481620A successfully refreshed from Google Patents.
US4481620A
Expired / Lapsed
US
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Pregrooved optical-disk
Assignee: TOKYO SIBAURA DENKI 72 HORIKAWA-CHO SAIWAI-KU KAWASAKI-SHI JAPAN A CORP OF JAPAN KK
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Filing: 1982-02-22
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Granted: 1984-11-06
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Expires: 2002-02-22
Abstract
Abstract An optical-disk according to an embodiment of the invention is disclosed. The optical-disk has a transparent substrate which has a surface in which a tracking groove is formed and which is made of a polymethyl methacrylate having a refractive index n 1 of about 1.49, a transparent layer of polystyrene which is formed on the transparent substrate and which has a refractive index n 2 of about 1.59, and a recording layer which is formed on the transparent layer of polystyrene and which is made of a substance which is melted by a pulse laser beam for recording, which becomes incident thereon through the transparent substrate and the transparent layer of polystyrene.
Inventors
- 👤 Teruo Murakami
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 16:09
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/24; G11B7/26; G11B7/241; G11B7/252; G11B7/257; G11B7/2572; G11B7/2575; G11B7/242; G11B7/243; G11B2007/24302; G11B2007/24316; G11B7/254; G11B2007/25408; G11B2007/25417; G11B7/253; G11B7/2531; G11B7/2533; G11B7/2542
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
160 words
A pregrooved optical-disk having a preformed tracking groove onto which a laser beam is radiated, said pregrooved optical-disk comprising: (a) a first layer of a transparent substance having a first refractive index n 1 having a surface containing said tracking groove; (b) a second layer of a transparent material having a second refractive index n 2 having a first surface in contact with said surface of said first layer and covering said tracking groove, said second layer having a substantially flat second surface opposite said first surface; (c) said tracking groove having depth which is a function of the difference between said first and second refractive indices; and (d) a recording layer provided on said second surface of said second layer, onto which the laser beam is incident through said first and second layers, said recording layer being of a substance that is meltable by said laser beam when an energy level of said laser beam exceeds a predetermined level.
Claim 2
Dependent Claim
160 words
A pregrooved optical-disk having a preformed tracking groove onto which a laser beam is radiated, said pregrooved optical-disk comprising: (a) a first layer of a transparent substance having a first refractive index n 1 having a surface containing said tracking groove; (b) a second layer of a transparent material having a second refractive index n 2 having a first surface in contact with said surface of said first layer and covering said tracking groove, said second layer having a substantially flat second surface opposite said first surface; (c) said tracking groove having depth which is a function of the difference between said first and second refractive indices; and (d) a recording layer provided on said second surface of said second layer, onto which the laser beam is incident through said first and second layers, said recording layer being of a substance that is meltable by said laser beam when an energy level of said laser beam exceeds a predetermined level.
Claim 3
Dependent Claim
32 words
A pregrooved optical-disk according to claim 1, wherein said first layer is a transparent substrate having the refractive index n 1 , and said second layer is formed on said transparent substrate.
Claim 4
Dependent Claim
62 words
A pregrooved optical-disk according to claim 1, wherein the depth of said tracking groove is defined by Δnd=(m/8±0.05)λ where d is said depth, Δn is the absolute value of the difference of the said refractive indices, m is an odd integer, and λ is the wavelength of said laser beam; wherein said depth of said tracking groove increases as said Δn decreases.
Claim 5
Dependent Claim
17 words
A pregrooved optical-disk according to claim 3, wherein Δn is in the range of 0.01 to 0.5.
Claim 6
Dependent Claim
17 words
A pregrooved optical-disk according to claim 4, wherein Δn is in the range of 0.02 to 0.2.
Claim 7
Dependent Claim
24 words
A pregrooved optical-disk according to claim 5, wherein the combination of said first layer, said second layer, and said recording layer forms a disk.
Claim 8
Dependent Claim
19 words
A pregrooved optical-disk according to claim 6, wherein said tracking groove extends in a circumferential direction of said disk.
Claim 9
Dependent Claim
27 words
A pregrooved optical-disk according to claim 5, further comprising a protective layer means, provided on said recording layer, for protecting said recording layer from the external atmosphere.
Claim 10
Dependent Claim
35 words
A pregrooved optical-disk according to claim 5, wherein said protective layer means is a predetermined substrate; said recording layer, said second layer and said first layer being sequentially formed on one surface of said substrate.
Claim 11
Dependent Claim
40 words
A pregrooved optical-disk according to claim 9, wherein said first surface of said second layer contains a projection corresponding to said tracking groove of said first layer, said first layer being formed on said first surface of said second layer.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-11-06 | 1988-05-07 | 1988-11-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-11-06 | 1992-05-07 | 1992-11-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-11-06 | 1996-05-07 | 1996-11-06 | $7700.00 | Window Closed / Lapsed |